The thin film transistor liquid crystal display devices (TFT-LCD) belong to a main kind of flat panel display devices (FPD).
Based on the direction of the electrical field for driving the liquid crystal, TFT-LCD can be divided into a vertical field type and a horizontal field type. For the vertical field type TFT-LCD, it is necessary to form pixel electrodes on an array substrate and form common electrodes on a color filter substrate. However, for the horizontal field type TFT-LCD, it is necessary to faun pixel electrodes and common electrodes on the array substrate. As a result, during manufacturing the array substrate of the horizontal field type TFT-LCD, as compared with the array substrate of the vertical field type TFT-LCD, additional masking process for forming the common electrodes is required. The vertical field type TFT-LCD can include a twist nematic (TN) type TFT-LCD. The horizontal field type TFT-LCD can include a fringe field switching (FFS) type TFT-LCD, an in-plane switching (IPS) type TFT-LCD and the like. The horizontal field type TFT-LCD, particularly FFS type TFT-LCD, has advantages of wide viewing angle, high aperture ratio and the like, and is applied widely to the field of the liquid crystal display device.
Currently, the array substrate of the FFS type TFT-LCD is manufactured by forming structural patterns using a plurality of patterning processes, each of which further comprises processes of exposing photoresist by using a mask, developing, etching and peeling off the remaining photoresist and the like. The etching process may comprise dry etching and wet etching. Therefore, the complexity of the process for manufacturing the array substrate of TFT-LCD is determined by the number of patterning processes, and thus reducing of the number of pattern processes would result in a decreased cost. The six patterning processes in the prior art comprise: pattering of a common electrode, patterning of gate lines and gate electrodes, patterning of an active layer, patterning of source electrodes/drain electrodes, patterning of via holes and patterning of pixel electrodes.
The five patterning processes in the prior art for manufacturing the array substrate of an FFS type TFT-LCD is as follows:
Step 1, depositing a first transparent conductive film and forming a pattern of a plate-like common electrode by an ordinary mask;
Step 2, depositing a first metal film and forming patterns of gate lines, gate electrodes and the common electrode by an ordinary mask;
Step 3, depositing a first insulating film, a semiconductor film, an impurity-doped semiconductor film and a second metal film sequentially, and forming patterns of an active layer (the semiconductor film and the impurity-doped semiconductor film), a TFT channel, source electrodes, drain electrodes and data lines by a dual tone mask;
Step 4, depositing a second insulating film, and forming patterns of via holes by using a second dual tone mask so as to form patterns of connection holes in the gate lines region of a PAD region, the data lines region of the PAD region and the common electrode region of the PAD region; and
Step 5, depositing a second transparent conductive film, and forming patterns of pixel electrodes with slits by an ordinary mask.